Rotary Valve System and Engine Using the Same

ABSTRACT

Rotary valve system for controlling communication with a port in an internal combustion engine which, in one disclosed embodiment, has a crankshaft, compression and expansion pistons connected to the crankshaft for reciprocating movement within compression and expansion chambers, a combustion chamber in which air from the compression chamber is combined with fuel and burned to produce an increased gas volume. The valve system has an outer valve member which is rotatively mounted in a bore and has an opening which moves into and out of communication with the port as the outer valve member rotates, an inner valve member rotatably mounted within the outer valve member with an opening at least partly overlapping the opening in the outer valve member, a flange extending along one edge of the opening in the inner valve member and through the opening in the outer valve member for sealing engagement with the wall of the bore, and means for effecting rotation of the valve members to change the degree of overlap between the openings and thereby control the timing and duration of communication between the openings and the port.

RELATED APPLICATION

Division of Ser. No. 11/372,978, filed Mar. 9, 2006, which claimed thepriority of:

-   -   Provisional Application No. 60/660,045, filed Mar. 9, 2005;    -   Provisional Application No. 60/660,046, filed Mar. 9, 2005,    -   Provisional Application No. 60/660,050, filed Mar. 9, 2005,    -   Provisional Application No. 60/760,478, filed Jan. 20, 2006,    -   Provisional Application No. 60/760,641, filed Jan. 20, 2006,    -   Provisional Application No. 60/760,642, filed Jan. 20, 2006.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention pertains generally to internal combustion engines and,more particularly, to a rotary valve system and an internal combustionengine utilizing the same.

2. Related Art

Although widely used in automotive engines and other internal combustionengines, conventional poppet valves have a number of limitations anddisadvantages. With the strong springs required to close them and holdthem shut and the camshafts, rocker arms, and/or other mechanismrequired to open them, standard valve trains can require a significantportion of an engine's output to operate them.

Since poppet valves usually extend into the firing chambers when open,they can limit the minimum chamber volume and thus prevent an enginefrom having maximum volumetric efficiency, and measures must be taken toensure that the valves do not collide with the pistons. Valve float canalso be a problem, and if a valve ever does get sucked into a cylinder,it can destroy the engine. Poppet valves may require periodicadjustment, and typically have relatively large heads which can obstructthe flow of both the fuel mixture and the exhaust gases. In addition, itis very difficult to vary the valve timing with poppet valves.

Heretofore, there have been attempts to use rotary valves andelectronically controlled valves instead of poppet valves in internalcombustion engines. However, they also have had limitations anddisadvantages which have limited their usefulness.

OBJECTS AND SUMMARY OF THE INVENTION

It is in general an object of the invention to provide a new andimproved rotary valve system and an internal combustion engine utilizingthe same.

Another object of the invention is to provide a rotary valve system andengine of the above character which overcome limitations anddisadvantages of valve systems and engines heretofore provided.

These and other objects are achieved in accordance with the invention byproviding a rotary valve system for controlling communication with aport in an internal combustion engine. The valve system has a firstrotary valve member with an opening which comes into registration withthe port during part of each revolution of the valve member, a secondrotary valve member disposed concentrically of the first valve memberand having an opening which at least partly overlaps with the opening inthe first valve member, a flange extending from one of the valve membersinto the opening in the other valve member, and a control for adjustingthe relative rotational positions of the valve members to change thedegree of overlap between the openings and thereby control the timingand/or duration of communication between the openings and the port. Insome embodiments, the first valve member is an outer sleeve which isrotatively mounted in a bore, and the second valve member, which can beeither a solid body or a sleeve, is rotatively mounted in the outersleeve, with the flange extending through the opening in the outersleeve and into sealing engagement with the wall of the bore.

In an embodiment for controlling communication between ports in twochambers of an internal combustion engine, the first valve member hasfirst and second openings that move into and out of communication withthe two ports, the second valve member has first and second openingswhich at least partly overlap with respective ones of the first andsecond openings in the first valve member, and the control adjusts therelative rotational positions of the valve members to change the degreeof overlap between the openings and thereby control the timing andduration of communication between the two chambers.

The valves are typically driven from the crankshaft or other outputshaft of the engine, with the opening in the first valve member defininga variable window in which valve can be open. The relative rotationalpositions of the two valve members are adjusted to control the overlapof the openings and, hence, when the valve opens or closes and how longit remains open. In some embodiments, the timing of the first valvemember is fixed relative to the position of the crankshaft and/or apiston, and the position of the second valve member is adjusted to varythe valve timing.

In one disclosed embodiment, the valve system is shown in conjunctionwith an engine having compression and expansion chambers, a separatecombustion chamber in which air from the compression chamber is combinedwith fuel and burned to produce an increased gas volume, an intake valvefor controlling air flow to the compression chamber, and outlet valvefor controlling air flow from the compression chamber to the combustionchamber, an inlet valve for controlling communication between thecombustion chamber and the expansion chamber, and an exhaust valve forcontrolling exhaust gas flow from the expansion chamber. In thatparticular embodiment, all four of the valves incorporate the invention.The valve system is not, however, limited to engines of that type, andit can also be used in conventional internal combustion engines,including engines in which combustion takes place in the same cylindersor chambers as compression and expansion.

Increased flow for low pressure gases can be provided by making theopenings in valves where pressure is lower wider than the openings invalves where pressure is higher. Thus, in the embodiment discussedabove, the intake valve has wider openings for allowing gas that is ator near atmospheric pressure to enter the compression chamber from anintake manifold, and the outlet valve has narrower openings for allowinghigh pressure gas to flow to the combustion chamber. Similarly, theinlet valve has narrower openings for allowing high pressure gas toenter the expansion chamber from the combustion chamber, and the exhaustvalve has wider openings for allowing gas that is at or near atmosphericpressure to be exhausted from the expansion chambers.

In embodiments where the engine has a plurality of compression and/orexpansion chambers, the valve members can be ganged together, with asingle valve member serving more than one chamber. Thus, for example, inan engine having a plurality of compression chambers, a common outersleeve with openings in different positions to provide the outlet valvefor each of them, with independently adjustable valve members within thesleeves for varying the timing and duration of each of the valves.Common valve members can also be used for different types of chambers,such as a compression chamber and an expansion chamber.

In some disclosed embodiments, relative rotation between the valvemembers is effected by a gear system which, in one embodiment, includesa first drive gear affixed to one of the inner valve member, a seconddrive gear affixed to the outer valve member, and a variable gear traininterconnecting the drive gears for rotation in unison while permittingthe drive gears to be advanced and retarded relative to each other.

In other disclosed embodiments, relative rotation between the valvemembers is effected by an endless drive element, such as a toothed beltor a chain, trained about a drive wheel and a wheel connected to one ofthe valve members with runs of the drive element between the wheels onopposite sides of the wheel connected to the one valve member, and meansfor differentially varying the relative lengths of the runs to advanceand retard the one valve member relative to the drive wheel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional view, somewhat schematic, of oneembodiment of an internal combustion engine with a rotary valve systemincorporating the invention.

FIG. 2 is an enlarged cross-sectional view of one of the valveassemblies in the embodiment of FIG. 1.

FIG. 3 is a plan view of one embodiment of a gear driven system foradjusting the timing and duration of the valve openings in theembodiment of FIG. 1.

FIGS. 4A and 4B are cross-sectional views similar to FIG. 2, showing thevalve members in different operative positions.

FIG. 5 is an isometric view, partly broken away, of the valve assemblyin the embodiment of FIG. 1.

FIG. 6 is an isometric view of one embodiment of a belt driven systemfor adjusting the timing and duration of the valve openings in theembodiment of FIG. 1.

FIG. 7 is an enlarged fragmentary cross-sectional view of the cylinderhead of an engine similar to the embodiment of FIG. 1, illustrating themanner in which the valve members are sealed.

DETAILED DESCRIPTION

In the drawings, the invention is illustrated in conjunction with a fourcylinder internal combustion engine which is described in greater detailin copending application Ser. No. 11/372,751, filed Mar. 9, 2006, thedisclosure of which is incorporated herein by reference. That engine hasa pair of compression cylinders 11, 12 and a pair of expansion cylinders13, 14 connected to opposite ends of a combustion chamber 16 which can,for example, be of a type disclosed in copending application Ser. No.11/372,737, filed Mar. 9, 2006, filed of even date, the disclosure ofwhich is incorporated herein by reference. The cylinders are formed inan engine block 17, with the upper ends of the cylinders being closed bya cylinder head 18 and the lower ends of the cylinders opening into acrankcase 19 in the lower portion of the engine block.

Reciprocating pistons 21-24 are mounted in the cylinders and connectedto a crankshaft 25 by connecting rods 26-29, with pistons 21, 22 servingas compression pistons in cylinders 11, 12 and pistons 23, 24 serving asexpansion pistons in cylinders 13, 14. For good balance, the two outerpistons (compression piston 21 and expansion piston 24) move up and downtogether, as do the two inner pistons (compression piston 22 andexpansion piston 23), with the two groups being substantially 180degrees out of phase with each other.

Although a four cylinder engine is shown, the valves will work with anynumber of cylinders in any internal combustion engine, and they can alsobe used in other valving applications, such as steam engines, wherevariable valve timing is desired.

Compression cylinders 11, 12 receive fresh air through an intakemanifold 31, with intake valves 32, 33 controlling communication betweenthe manifold and the cylinders. Cylinders 11, 12 also communicate withthe inlet end of combustion chamber 16 via a manifold 34, withcommunication between the cylinders and that manifold being controlledoutlet valves 36, 37. The outlet end of combustion chamber 16communicates with expansion cylinders 13, 14 via a manifold 39, withinlet valves 41, 42 controlling communication between the chamber andthose cylinders. Exhaust gases are expelled from the expansion cylindersthrough an exhaust manifold 43, with communication between the cylindersand the manifold being controlled by exhaust valves 46, 47.

Air is drawn into the compression chambers on the downstroke of pistons21, 22, then compressed and thereby heated on the upstroke of thepistons and injected into the inlet end of combustion chamber 16. In thecombustion chamber, the hot, compressed air mixes with fuel introducedinto the chamber through a fuel inlet to form a mixture which burns andproduces a volumetric increase throughout the chamber. The expandinggases leaving the combustion chamber drive pistons 23, 24 in a downwarddirection in the expansion cylinders, and spent gases are expelledthrough exhaust manifold 43 on the upstroke of those pistons.

In one presently preferred embodiment, the sizing of the compression andexpansion cylinders, the movement of the pistons within the cylinders,and the timing of the valves are such that the pressure within thecombustion chamber remains substantially constant throughout theoperating cycle of the engine, although some pressure spiking can occurand may even be desirable in some cases.

As best seen in FIG. 2, each of the valves has an outer sleeve 51 whichis rotatively mounted in a bore 49 in cylinder head 18 and an innervalve member 52 which is rotatively mounted in the outer sleeve. In theembodiment illustrated, the inner valve member is also a sleeve, but itcould be a solid body, if desired. The bore opens through the lower sideof the head to form a port 53 in communication with the cylinder below,a manifold passageway 54 communicates with the bore on the side oppositethe port.

The outer sleeve has a pair of diametrically opposed slotted openings56, 57 which move into and out of registration with port 53 andpassageway 54 as the sleeve rotates. Inner valve member 52 also has apair of diametrically opposed slotted openings 58, 59, with a radial lipor flange 61, 62 extending along one edge of each of the openings in theinner member and through one of the openings in the outer sleeve forsealing engagement with the wall of the bore.

The openings in outer sleeve 51 define a window during which the valvecan be open. This window corresponds to the period of time during whichone of the openings in the outer sleeve is aligned with the port 53 andthe other is aligned with the manifold passageway 54. The valve isactually open only when the openings in inner valve member 52 also alignwith port 53 and manifold passageway 54. The position of the inner valvemember 52 relative to the outer sleeve 51 is varied to control when thevalve opens or closes and how long it remains open during the window.

In some applications, it may be desirable to have the openings offsetradially from each other, rather than being aligned diametrically.Offsetting the openings will limit the flow through them to some extentbut will permit the valves to remain open for a longer time than whenthe openings are aligned.

It may also be desirable in some applications to make lip seals 61, 62in a way such that the valve is not completely closed in its most closedposition. That can be done, for example, by forming grooves in thesealing surfaces or by putting stops on the seals to prevent the valvefrom closing fully. This can be useful during very low load conditionssuch as compression release engine braking, commonly known as “Jakebraking”, where it can be beneficial to have a small amount of air enterthe combustion chamber and burn. This will keep the combustion chamberhot and ready for use even after long periods of very low loadconditions. In addition, the small flow of air may help avoidoverpressure conditions in the event of a control failure.

In the embodiment illustrated in FIG. 1, the side walls of the slottedopenings lie in radial planes, and the openings in the valves wherepressure is lower are shown as being wider than the openings in thevalves where pressure is higher. Thus, in this example, the intakevalves have wider openings for allowing gas that is at or nearatmospheric pressure to enter the compression chambers from an intakemanifold, the outlet valves have narrower openings for allowing highpressure gas to flow to the combustion chamber. Similarly, the inletvalves have narrower openings for allowing high pressure gas to enterthe expansion chambers from the combustion chamber and wider openingsfor allowing gas that is at or near atmospheric pressure to be exhaustedfrom the expansion chambers.

The outer sleeve is driven from the crankshaft by suitable means such asgears, belts or chains, and means is provided for rotating the innervalve member relative to the outer sleeve to change the degree ofoverlap between the openings and thereby control the timing and durationof communication between the openings and the port.

In the embodiment shown in FIG. 3, a drive gear 64 is mounted on outersleeve 51 and driven from the crankshaft through a gear train (notshown) which, in this example, provides a 2:1 reduction in speed betweenthe crankshaft and the valve so that the valve makes one revolution foreach two revolutions of the crankshaft. During one revolution of thecrankshaft, openings 56, 58 are aligned with port 53 and openings 57, 59are aligned with passageway 54, and during the next revolution, openings57, 59 are aligned with the port and openings 56, 58 are aligned withthe passageway.

A variable gear train 66 interconnects the two valve members forrotation in unison while permitting inner sleeve 52 to be advanced andretracted relative to outer sleeve 51. This train includes drive gears67, 68 which are affixed to respective ones of the two sleeves, and atiming gear 69 which is mounted on inner sleeve between the drive gearsand is free to rotate about that sleeve. An axle 71 extends in a radialdirection from timing gear 69 and carries a planetary gear 72 whichmeshes with drive gear 67 on outer sleeve 51 and with an idler gear 73which is rotatively mounted on inner sleeve. Idler gear 73 is a doublebevel gear and is coupled to drive gear 68 by another idler gear 74which rotates about a radially extending axle 76 mounted on cylinderhead 18. Timing gear 69 is driven by a stepping motor 77 and a drivegear 78 on the motor shaft.

As outer sleeve 51 is driven by the crankshaft, inner sleeve 52 rotatesin unison with it as long as timing gear 69 remains stationary, with therotation being coupled from drive gear 67 to drive gear 68 by planetarygear 72 and idler gears 73, 74. In that regard, it will be noted thatplanetary gear 72 drives idler gear 73 at the same speed as drive gear67, but in the opposite direction, and that idler gear 74 reverses thedirection again so that drive gear 68 turns at the same speed and in thesame direction as drive gear 67.

When timing gear 69 is rotated by positioning motor 77, axle 71 and theplanetary gear carried by it precess about the axis of the sleeves. Asthe planetary gear moves relative to drive gear 67, it turns about itsaxis, and that rotation is imparted to idler gear 73 to advance orretard that gear relative to drive gear 67. That movement is reversedand transferred to drive gear 68 and, hence, to inner sleeve 52 by idlergear 74.

By advancing and retarding the position of inner sleeve 52 relative toouter sleeve 51, the timing and duration of the valve opening can becontrolled. Thus, in FIG. 4A, the sleeves are shown with openings 58, 59fully aligned with or overlapping openings 56, 57, which maximizes theduration of the valve opening. With the sleeves in this position, lipsor flanges 61, 62 extending along the trailing edges of openings 58, 59,and the sleeves rotating in a clockwise direction, the valve opens whenthe leading edges 81, 82 of openings 56, 57 reach the near edge 83 ofport 53 and close when flanges 61, 62 reach the far edge 84 of the port.

When inner sleeve 52 is advanced relative to outer sleeve 51, asillustrated in FIG. 4B, the valve still opens when the leading edges ofopenings 56, 57 reach the near edge of the port and closes when flanges61, 62 reach the far edge. However, the flanges will reach the far edgeat an earlier point in the rotation of the outer sleeve, so the valveremains open for a shorter period of time and closes sooner.

If the flanges or lips are positioned along the leading edges ofopenings 58, 59, rather than the trailing edges and the valve stillrotates in the same direction, then the valve will open when the flangesreach the near edge of the port and close when the trailing edges ofopenings 56, 57 reach the far edge. In that case, the opening point isadjustable and the closing point is fixed.

If desired, a similar system can also be utilized to advance and retardthe outer sleeves relative to the crankshaft to provide independentlyvariable opening times and closing times for the valves. This providesan unprecedented level of control for a wide range of engine loads andconditions.

FIG. 1 is schematic in that for purposes of illustrating the two valvesin each cylinder and their positions relative to the pistons, the valvesare shown as extending crosswise of the engine, whereas in thatparticular embodiment they actually extend in a lengthwise direction asshown in FIG. 5.

Thus, in the four cylinder engine of FIG. 1, the valves are alignedalong two parallel axes which extend side-by-side above the cylinders,with four valves along each and the number of valves being dependent onthe number of cylinders. In the embodiment illustrated, each outersleeve and each inner sleeve serves two valves, with the two outersleeves on each side being connected together at their inner ends forrotation in unison. The inner sleeves rotate independently of eachother, but are coupled at their outer ends to the outer sleeves in themanner described above, with a separate positioning motor for each. Eachpair of intake, outlet, inlet, and exhaust valves has an independentdrive mechanism to allow independent control of each type of valve.

As shown in FIG. 5, outer sleeves 51 a and 51 b are connected togetherat their inner ends by a coupling 86, with positioning motors 77 a, 77 band gear trains 66 a, 66 b for adjusting the relative positions of theinner sleeves. Likewise, outer sleeves 51 c, 51 d are connected togetherat their inner ends by a coupling 87, with positioning motors 77 c, 77 dand gear trains 66 c, 66 d for adjusting the relative positions of thesleeves in them. In this embodiment, the air intake valves 32, 33 forcompression cylinders 11, 12 are formed by outer sleeve 51 a and innersleeve 52 a, the outlet valves 36, 37 for compression cylinders 11, 12are formed by outer sleeve 51 c and inner sleeve 52 c, the inlet valves41, 42 for expansion cylinders 13, 14 are formed by outer sleeve 51 dand inner sleeve 52 d, and the exhaust valves 46, 47 for expansioncylinders 13, 14 are formed by outer sleeve 51 b and inner sleeve 52 b.

In the embodiment of FIG. 6, the valve system is driven from thecrankshaft of the engine by means of a belt or chain system 88 whichpermits the inner valve members to be advanced and retarded relative tothe outer sleeves. The valve system and engine are similar those in theembodiment of FIG. 5, but without the gear trains and positioning motorsfor controlling the valve timing. The drive system is shown for thevalves at one end of the engine only, it being understood that a similarsystem is also provided for the valves at the other end.

Outer sleeves 51 a, 51 c are driven by an endless drive element in theform of a toothed drive belt or chain 89 which is trained about a cogwheel or sprocket 91 on crankshaft 25 and about cog wheels or sprocket92, 93 on the outer sleeves, with an idler wheel or sprocket 94 formaintaining proper tension in the belt.

Each of the inner valve members 52 a, 52 c is driven by an endless driveelement such as a toothed drive belt or chain 96 which is trained aboutcog wheels or sprockets 97, 98 on the crankshaft and valve member, withmeans for differentially adjusting the relative lengths of the runs ofthe belt or chain 99, 101 between the cog wheels or sprockets. In theembodiment illustrated, this means comprises a pair of idler wheels orsprockets 102, 103 which can be moved back and forth in a directiongenerally perpendicular to the runs. By simultaneously moving idlerwheel or sprocket 102 to the left and idler wheel or sprocket 103 to theright, the length of run 99 is decreased and the length of run 101 isincreased. With drive pulleys or sprockets 91 and 97 locked together onthe crankshaft, the shift in the belt or chain causes cog wheel orsprocket 98 and inner valve member 52 c to advance in a clockwisedirection relative to outer sleeve 51 c. The inner valve member 52 c canbe shifted in a counter-clockwise direction, or retarded, by movingidler wheel or sprocket 102 to the right and idler wheel or sprocket 103to the left, which increases the length of run 99 and decreases lengthof run 101.

If one of the idler wheels or sprockets is spring-loaded toward itsextended position (i.e., the position which increases the length of therun trained about it), it is only necessary to adjust the position ofthe other idler wheel or sprocket in order to adjust the valve timing.Thus, for example, with idler wheel or sprocket 103 biased toward itsextended position, as illustrated schematically by spring 106, valvemember 52 c can be advanced simply by moving idler wheel or sprocket 102to the left and retarded by moving idler wheel or sprocket 102 to theright. As idler wheel or sprocket 102 moves to the left, the springmoves idler wheel or sprocket 103 to the right, thereby increasing thelength of run 101 relative to run 99. When idler wheel or sprocket 102moves to the right and increases the length of run 99, the spring allowsidler wheel or sprocket 103 to move to the left with a correspondingdecrease in the length of run 101.

If desired, a similar system of idler wheels or sprockets can beutilized to change the relative lengths of the belt 89 which is trainedabout the cog wheels or sprockets 92, 93 affixed to the outer valvemembers or sleeves 51 a, 51 c to provide independently variable openingtimes and closing times for the valves.

The timing of the valves can be controlled by a control system such asthat disclosed in Ser. No. 11/372,751, filed Mar. 9, 2006, thedisclosure of which is incorporated herein by reference. Such a systemhas sensors for monitoring temperature and pressure in the chambers andin other parts of the engine and a computer or other controller forcontrolling actuators that move the idler wheels or sprockets to adjustthe timing of the valves in accordance with temperature, pressure, loadand other operating conditions.

In the embodiment of FIG. 7, cylinder head 111 is split horizontallyinto two sections 111 a and 111 b, with circular valve bores 112 formedpartially in each of the two sections. Outer valve sleeves 113 arerotatively mounted in the bores and inner valve members 114 arerotatively mounted within the sleeves. The sleeves have slotted openings116 on opposite sides thereof, and the valve members have generallycylindrical bodies with openings 117 extending through the bodies.Inserts 118 are mounted in openings 117 and provide seals between thevalve members and sleeves. The inserts also extend through the slottedopenings in the sleeves to form lips or flanges 119 which extend throughthe openings in the outer sleeves and form seal with the bores.

Bores 112 are formed in part by inserts 121, 122 which are mounted invertically extending bores 123, 124 that intersect the valve bores andform ports for the valves. Bores 123, 124 are stepped, and the insertsare mounted in enlarged sections of the bores above and below the valvesleeves, with C-ring seals 126 between the inserts and the shoulders ofthe bores in which they are mounted. With their C-shaped cross section,seals 126 are flexible enough to provide a spring force which holds theinserts and sleeves together and also provide compensation for thermalexpansion and wearing of the parts. Seals 128 provide sealing betweenthe inserts and the sleeves. The inserts can be fabricated of a ceramicmaterial or any other suitable material.

The lower portions of bores 123, 124 communicate directly with thecylinder (not shown) beneath the valves, and the upper portions of thebores communicate with the manifolds.

The inserts and seals are installed along with the valves while the twosections of the head are apart, and they are retained in place by thehead when it is assembled. As in the embodiment of FIG. 1, valve sleeves113 are free to rotate within bores 112, with the positions of valvemembers 114 being adjustable relative to sleeves 113 to vary the timingand duration of the valve openings.

Since the valves do not extend into the cylinders when they open, theydo not prevent the pistons from traveling all the way to the tops of thecylinders like poppet valves do, even when they are open. Hence, theonly limitation to full piston travel is the need for a small toleranceor clearance to prevent the pistons from striking the head due tothermal expansion or extension at higher engine speeds. This clearancecan, for example, be on the order of about 0.010 inch to 0.200 inch, andtypically does not need to be more than about 0.015 inch. Hence, theminimum volumes of the cylinders can be much closer to zero than theyare in other engines.

Although a rotary valve has the ability to open when the piston is attop dead center (TDC) and close when the piston at bottom dead center(BDC), that may not be the best way to operate the valves in a givenengine since it can result in compressed gases being blown out throughthe intake and/or exhaust manifolds. In an engine of the type shown inFIG. 1, for example, opening the intake valve at top dead center wouldallow compressed air to escape, thereby wasting the work done incompressing it and compromising the efficiency of the engine.

It is, therefore, preferable to retard the opening of the intake valveuntil the air in the cylinder has expanded enough to be at or nearatmospheric pressure. In this way, the work done to compress the gas isrecovered as the gas pushes against the piston at the top of itsdownstroke.

For example, an engine with a 12.5:1 compression ratio and a 3.76″stroke may have a 0.015″ clearance between the crown of the piston andthe cylinder head. If the intake valve were opened at TDC, gas at apressure of 504 p.s.i. would escape and be wasted. If, however, theopening of the intake valve is delayed until the piston has moved downto the point where the gas has expanded to 12.5 times the volume at TDC,then the pressure of the gas above the piston would be at or nearatmospheric, no gas would be lost out the intake valve, and the enginewould still have the same amount of air in the cylinder at BDC even withthe delayed opening of the intake valve.

In the foregoing example, the volume of the gas has expanded to 12.5times the TDC volume when the piston has traveled 11.5×0.015″, or0.173″, which is 4.6 percent of the 3.76″ stroke and 21.5 degrees ofcrankshaft rotation. With this delayed opening, the slotted openings 56,57 in the intake valves can be substantially narrower, with the leadingedges of the openings being moved back.

The invention has a number of important features and advantages. Priorattempts at building rotary valves with an adjustable inner memberwithin an outer sleeve were not successful because of leakage betweenthe inner member and the outer sleeve. The invention overcomes thatproblem with the sealing lip or flange which extends from the inside ofthe inner member to the outside of the sleeve, thereby preventingleakage between the two members. This provides a truly variable valveopening or closing without major leaks.

Either the opening positions or the closing positions of the valves canbe adjusted, depending upon which side of the openings the sealingflanges or lips are on, and the opening or closing positions can beadjusted by as much as 180 degrees. Thus, the opening positions can beadjusted without affecting the closing positions, or the closingpositions can be adjusted without affecting the opening positions. Allof the valves can be adjusted independently and while the engine isrunning. The full adjustability of the valve system permits constantmatching of engine performance over a wide range of engine load andspeed.

Since the inner member and the outer sleeve rotate together except whenthe load and speed of the engine change, there is very little wearbetween the parts. With less wear, the valves can use dry lubricationrather than liquid lubrication, thereby avoiding the problem of oilleaking into cylinders and fouling plugs and/or building up carbondeposits. Without oil, the parts can run hotter, which reduces heat lossand improves efficiency. It also reduces oil burning and eliminatespollution due to the burning of oil in the valve system.

Since there are no springs, the valves cannot float, and engine speedand power are not compromised at higher RPM as they are withconventional valves. Eliminating the springs also reduces the powernecessary to run the valve train, which further increases the availablehorsepower and efficiency of the engine. Moreover, the rotary valvesallow the engine to operate at higher RPM than one with reciprocatingvalves.

The rotary valves of the invention are not constrained by the spacelimitations of round poppet valves and can have large, rectangular portswhich provide significantly greater flow and also improve engineefficiency. It is also beneficial not to have to force gases around themushroom shaped heads of poppet valves.

Since the valves do not extend into the cylinders, they do not preventthe pistons from traveling all the way to the tops of the cylinders likepoppet valves do, and there is no danger of the valves colliding withthe pistons in the event of a mechanical malfunction. This permits fullutilization of the cylinder volume and provides both high volumetricefficiency and high engine efficiency.

Although the invention has been disclosed with specific reference to anengine having a separate chamber in which combustion occurs, the valvesystem can also be utilized advantageously in internal combustionengines where combustion takes place in the same chambers as compressionand expansion. In addition to being adjustable, the system has fewermoving parts than a poppet valve system, and the rotary valves take lesswork to operate than poppet valves. The system requires less space thana poppet valve system. The valves can open and close faster than poppetvalves and can also operate at higher engine speeds, or RPM. Moreover,there is no danger of valve float, and engine breathing is better thanwith conventional valve systems. Hence, the system will improve the fuelefficiency of and reduce pollution from such engines.

It is apparent from the foregoing that a new and improved rotary valvesystem and an engine utilizing the same have been provided. While onlycertain presently preferred embodiments have been described in detail,as will be apparent to those familiar with the art, certain changes andmodifications can be made without departing from the scope of theinvention as defined by the following claims.

1. A rotary valve system for controlling communication with a port in aninternal combustion engine, comprising: an outer valve member which isrotatively mounted in a bore and has an opening which moves into and outof communication with the port as the outer valve member rotates, aninner valve member rotatably mounted within the outer valve member withan opening at least partly overlapping the opening in the outer valvemember, a seal member carried by the inner valve member in sealingengagement with the outer valve member and having a flange portion thatextends through the opening in the outer valve member and makes sealingengagement with the wall of the bore, and means for effecting relativerotation between the valve members to change the degree of overlapbetween the openings and thereby control the timing and duration ofcommunication between the openings and the port.
 2. The rotary valvesystem of claim 1 wherein the outer valve member is a sleeve withslotted openings on opposite sides thereof.
 3. The rotary valve systemof claim 1 wherein the inner valve member has a cylindrical body throughwhich the opening in the inner valve member extends.
 4. The rotary valvesystem of claim 1 wherein the bore is formed in a pair of insertsmounted in an enlarged section of a stepped bore with shoulders atopposite ends of the enlarged section and C-ring seals between theinserts and the shoulders.
 5. The rotary valve system of claim 4 whereinthe C-ring seals are flexible enough to provide a spring force whichurges the inserts together against the outer valve member and alsoprovide compensation for thermal expansion and wearing of the outervalve member and the inserts.
 6. An internal combustion engine havingcompression and expansion pistons constrained for reciprocating movementwithin compression and expansion chambers, a combustion chamber in whichair from the compression chamber is combined with fuel and burned toproduce an increased gas volume, an intake valve for controlling airflowto the compression chamber, and outlet valve for controlling air flowfrom the compression chamber to the combustion chamber, an inlet valvefor controlling communication between the combustion chamber and theexpansion chamber, and an exhaust valve for controlling exhaust gas flowfrom the expansion chamber, at least one of the valves comprising anouter valve member which is rotatively mounted in a bore and has anopening which moves into and out of communication with the chamber asthe outer valve member rotates, an inner valve member rotatably mountedwithin the outer valve member with an opening at least partlyoverlapping the opening in the outer valve member, a seal member carriedby the inner valve member in sealing engagement with the outer valvemember and having a flange portion that extends through the opening inthe outer valve member and makes sealing engagement with the wall of thebore, and means for effecting relative rotation between the valvemembers to change the degree of overlap between the openings and therebycontrol the timing and duration of communication between the openingsand the chamber.
 7. The internal combustion engine of claim 6 whereinthe outer valve member is a sleeve with slotted openings on oppositesides thereof.
 8. The internal combustion engine of claim 6 wherein theinner valve member has a cylindrical body through which the opening inthe inner valve member extends.
 9. The internal combustion engine ofclaim 6 wherein the bore is formed in a pair of inserts mounted in anenlarged section of a stepped bore with shoulders at opposite ends ofthe enlarged section and C-ring seals between the inserts and theshoulders.
 10. The internal combustion engine of claim 9 wherein theC-ring seals are flexible enough to provide a spring force which urgesthe inserts together against the outer valve member and also providecompensation for thermal expansion and wearing of the outer valve memberand the inserts.
 11. An internal combustion engine having a cylinder,crankshaft, a piston connected to the crankshaft for reciprocatingmovement within the cylinder, an outer valve member rotatively mountedin a bore with an opening which moves into and out of communication thecylinder as the outer valve member rotates, an inner valve memberrotatably mounted within the outer valve member with an opening at leastpartly overlapping the opening in the outer valve member, a seal membercarried by the inner valve member in sealing engagement with the outervalve member and having a flange portion that extends through theopening in the outer valve member and makes sealing engagement with thewall of the bore, and means for effecting relative rotation between thevalve members to change the degree of overlap between the openings andthereby control the timing and duration of communication between theopenings and the cylinder.
 12. The internal combustion engine of claim11 wherein the outer valve member is a sleeve with slotted openings onopposite sides thereof.
 13. The internal combustion engine of claim 11wherein the inner valve member has a cylindrical body through which theopening in the inner valve member extends.
 14. The internal combustionengine of claim 11 wherein the bore is formed in a pair of insertsmounted in an enlarged section of a stepped bore with shoulders atopposite ends of the enlarged section and C-ring seals between theinserts and the shoulders.
 15. The internal combustion engine of claim14 wherein the C-ring seals are flexible enough to provide a springforce which urges the inserts together against the outer valve memberand also provide compensation for thermal expansion and wearing of theouter valve member and the inserts.
 16. An internal combustion enginehaving a chamber of variable volume, an outer valve member which isrotatively mounted in a bore and has an opening which moves into and outof communication with the chamber as the outer valve member rotates, aninner valve member rotatably mounted within the outer valve member withan opening at least partly overlapping the opening in the outer valvemember, a seal member carried by the inner valve member in sealingengagement with the outer valve member and having a flange portion thatextends through the opening in the outer valve member and makes sealingengagement with the wall of the bore, and means for effecting relativerotation between the valve members to change the degree of overlapbetween the openings and thereby control the timing and duration. 17.The internal combustion engine of claim 16 wherein the outer valvemember is a sleeve with slotted openings on opposite sides thereof. 18.The internal combustion engine of claim 16 wherein the inner valvemember has a cylindrical body through which the opening in the innervalve member extends.
 19. The internal combustion engine of claim 16wherein the bore is formed in a pair of inserts mounted in an enlargedsection of a stepped bore with shoulders at opposite ends of theenlarged section and C-ring seals between the inserts and the shoulders.20. The internal combustion engine of claim 19 wherein the C-ring sealsare flexible enough to provide a spring force which urges the insertstogether against the outer valve member and also provide compensationfor thermal expansion and wearing of the outer valve member and theinserts.
 21. A rotary valve system for controlling communication with aport in an internal combustion engine, comprising: a first rotary valvemember having an opening which comes into registration with the portduring part of each revolution of the valve member; a second rotaryvalve member disposed concentrically of the first valve member andhaving an opening which at least partly overlaps with the opening in thefirst valve member; a seal member carried by the first valve member insealing engagement with the second valve member; and a control foradjusting the relative rotational positions of the valve members tochange the degree of overlap between the openings and thereby controlthe timing and duration of communication between the openings and theport.
 22. The rotary valve system of claim 21 wherein the first valvemember is a sleeve with slotted openings on opposite sides thereof. 23.The rotary valve system of claim 21 wherein the second valve member hasa cylindrical body through which the opening in the second valve memberextends.
 24. The rotary valve system of claim 21 wherein the bore isformed in a pair of inserts mounted in an enlarged section of a steppedbore with shoulders at opposite ends of the enlarged section and C-ringseals between the inserts and the shoulders.
 25. The rotary valve systemof claim 24 wherein the C-ring seals are flexible enough to provide aspring force which urges the inserts together against the outer valvemember and also provide compensation for thermal expansion and wearingof the outer valve member and the inserts.